1. TECHNICAL FIELD
The present invention relates to an air cleaner tank for enclosing an air filter. In particular, the invention relates to a high efficiency truck air cleaner tank.
2. PRIOR ART
An air cleaner tank is an airtight housing for a replaceable filter element. Air enters the housing and passes through the filter element before leaving the housing through an outlet which supplies air to the engine. Conventional air cleaner tanks are cylindrical metal tanks having a cylindrical air filter element. The engine draws air through the air cleaner tank by creating a high vacuum at the tank outlet. The air filter element removes solid contaminants from the engine supply air to prevent damage to the engine. Unfiltered air may reach the engine if the air cleaner tank is not airtight or if air entering the tank through the inlet duct is permitted to circumvent the filter element.
Air cleaner tanks currently in use on trucks have metal housings with one removable end for periodic replacement of the air filter element. The removable end of the air cleaner tank must be attached to the housing so as to form an airtight seal. In prior art air cleaner tanks the non-removable end of the tank is sealed by welding and the removable end (usually at the top) is secured by welded studs on the housing. Leakage is prevented by providing a gasket between the top cover and the housing and by bolting the cover to the housing with four to eight bolts that are carefully tightened according to torque specifications. Improper installation of the tank cover frequently results in cover warpage and leakage about the top of the housing. If air is permitted to leak into the housing about the cover it can then flow directly to the engine without passing through the air filter element.
Another problem with prior art cleaners is that the air filter element can be improperly located within the housing, permitting air to circumvent the air filter element. The high vacuum developed at the outlet of the tank could cause the air filter element to be pulled towards the outlet and reduce the efficiency of the air filter element by only using a limited portion of the element. Similarly, vibration or shocks can cause the air filter element to be shifted out of its optimum operating position.
In the prior art air cleaner tanks the base is not removable from the housing, which necessitates removal of the cover to replace the air filter element. Replacement of an air filter element is complicated by the need to remove or bend the duct which was attached to the cover before removing the cover from the top of the housing. If the air cleaner duct is the rigid type of duct it must be removed prior to disassembly of the cover from the housing. If the duct is flexible it can be twisted when the cover is removed from the housing, but this causes wear and tear on the duct.
When tightening the cover onto the housing great care must be exercised in securing the bolts so that the cover is not warped and the gasket is not damaged during installation. Damage to the cover or gasket is difficult to check in prior art systems, and once the cover is secured to the housing it is seldom checked for adequacy of the seal.
Prior art air cleaner tanks are heavy metal structures that must be strong to resist denting from foreign objects impacting the exterior. The cover and housing must also be strong enough to prevent distortion when the cover is bolted to the housing. Since the air cleaner tank is normally mounted exteriorly of the truck it must resist denting and corrosion. If a truck is involved in a minor accident or is hit on the air cleaner tank by a stone it can become dented which could make replacement of the filter element difficult and the creation of a complete seal impossible.